This invention relates to alignment structures for photographic apparatus. More particularly it relates to a self-aligning carriage as might be used to align, position, and support a photographic enlarger or other projection device which is operatively connected to a vertical column, for smooth and accurate movement therealong.
In some photographic applications it is common to provide a vertical support structure which permits adjustable positioning therealong of a photographic apparatus, such as a camera, enlarger, or projector. For example, an overhead enlarger may be vertically positioned over a photosensitive material, such as print paper, for exposure to light from the enlarger that has been projected through an image bearing medium, such as a negative, transparency, pattern or grid. For both image clarity and high resolution it is necessary to maintain the enlarger and its optical system in true alignment with the photosensitive paper. Thus, it is necessary that the apparatus be in constant, accurate three-dimensional alignment with respect to the vertical column, which in turn results in proper alignment with the photosensitive paper. On the other hand, the enlarger must be easily vertically adjustable to accommodate various sized transparencies and to provide multiple print sizes.
In the known photographic apparatus support structures, wheeled carriages have been arranged for vertical motion along structurally defined paths with little or no means for correcting play, misalignment, or slack resulting from wear and tear to rollers, bearings and tracks over time. Where employed, prior art alignment structures have either been complex or required continuing observation and manual adjustment. Indeed, some of the known support systems merely provided for angular alignment around a vertical support, making no provision for coaxial alignment.